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<h1>Logging</h1>

<p>In testing a large circuit, and for documenting a circuit's
behavior, a log of past circuit behavior can be useful. This is the purpose for
Logisim's logging module, which allows you to select components whose
values should be logged; optionally, you can specify a file into which
the log should be placed.</p>

<p>Another way to test a circuit is using a <strong>test vector</strong>.
Logisim's test vector module allows you to load a file specifying
circuit inputs and the values that should be output by the circuit.
Logisim will run the simulation and compare the actual outputs against
the desired outputs. Currently, test vectors are only designed to work
for combinational circuits.</p>

<p><strong>Note:</strong> The logging and test vector modules are in
alpha phase; they may be buggy, and they are subject to significant
changes in the future. While bug reports and suggestions are welcome
for all of Logisim, they are particularly welcome concerning these
relatively new features. If you do not send comments, then they will
likely not change.</p>

<p>You can enter the test vector module via the Test Vector... option
from the Simulate menu. See <a href="test.html">Test Vectors</a> for
documentation on how to use this module.</p>

<p>You can enter the logging module via the Logging...
option from the Simulate menu. It brings up a window with three tabs.</p>
<center>
<img src="../../../img-guide/log-selection.png" width="466" height="387">
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<p>We will discuss each of these tabs separately.</p>
<blockquote>
	<a href="selection.html">The Selection tab</a>
	<br><a href="table.html">The Table tab</a>
	<br><a href="file.html">The File tab</a>
</blockquote></p>

<p>Each project has only one logging window; when you switch to viewing
another circuit within the project, the logging window switches
automatically to logging the other circuit instead. That is, it does
this unless you are <a href="../subcirc/debug.html">moving up or down
within the same simulation</a>, in which case the logging module does
not change.</p>

<p>Note that when the logging module switches to logging another
simulation, it will cease any logging into a file. Should you switch
back to the simulation again, it will remember the configuration for
that simulation, but you will need to re-enable the file logging
manually.</p>

<p><strong>Next:</strong> <a href="selection.html">The Selection tab</a>.</p>

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